Range surface unit



p E. w. BEGGS 2,329,451

RANGE SURFACE UNIT Filed Sept. 27, 1940 2 Sheets-Sheet 1 INVENTOR EUGENE W. Bsaas.

ATTOR Sept. 14, 1943. E. w. BEGGS 2,329,451

RANGE SURFACE UNIT Filed Sept. 27, 1940 2 Sheets-Sheet 2 5'9. 5. /a 24 27 28 .9 is 2.9 28 54 A? 26 25 a 623/ it 47 45 Z 2Z6 4 58 an 42 a 48 L5 51 A0 M /a 46 6 a 14 mvzmoR WEE E W. B

UGENE EGGS ATTOR Y Patented Sept. 1'4, 1943 UN ITED STATES RANGE SURFACE UNIT Eugene W. Beggs, Glen Ridge, N. J., assignor'to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., aicorporation of Pennsylvania Application September 27, 1940, Serial No. 358,596

10 Claims. f (Cl; 219-37) indirect contact with the heating plate or surface,

the heating element is generally of a high-coldresistance material. The heating element, due to its high-cold-resistance, large mass and high conduction and radiation losses, which prevail with those elements known to the art, comes up to heat slowly, resulting in an undesirable appreciable time lag between the initial application of current and the time at which the heating element and the associated heating surface arrive at their maximum desired operating temperature, 3,,

and, due to the losses mentioned are relatively inefficient. Such range surface units are accordingly too slow in their operation in that they come to heat too slowly, and are also too'expensive in that they are less efficient .and are short-lived,

due to oxidation of the heating element,- requiring frequent replacements by reason of the heating elements burning out. It is, therefore, an object of my invention to provide a range surface unit,

or the like, which will comeup to the desired cooking temperature very quickly after the time of application of power to the heating element, and will cook more efiiciently and cheaply, and to provide a heating element located therein operated either in vacuum or in a suitable atmosphere of inert gas at any desirable pressure, resulting in a, long average life for such elements and heating units, as well as in a reduced cost thereof.

It is likewise old in the art to use a lamp or radiant element for heating purposes, in combination with a reflector located in such .aposition as to direct substantially all the heat radiated from such lamp in a predetermined direction. However, with those heating units of this type known to the art, the reflector must be open and the lamp exposed to permit convection of air from the lamp and for permitting ready replacement thereof. This condition makes it practically impossible to keep the reflector clean and polished throughout its life and to protect the lamp or radiant element from being broken due to the accidental splashing or dropping of moisture or liquids upon such lamp and reflector. Also, when using a glass-type lamp, the lamp may fail due to the softening and distortion of its glass bulb caused by the excessive heat within the area enclosedby the reflectorwhen the open, end is closed by the cooking utensil, or when cov-p ered by a secondary plate. It is, therefore, a further object of my invention to provide a heating unit having a reflector and heating element sealed'therein in such a manner that the reflector and heating element will be protected from any foreign matter that the operator might spill upon the heating unit, and that such reflector and heating element will be protected from all mechanical injury while, at the same time, a suitable controlled atmosphere (inert or high-vacuum) is employed.

*Afurther object of my invention is to provide a heating unit which'willheat the central portion of the top plate or cooking surface quicker and to ahigher temperature than the balance of said'top plate and the support therefor, which guarantees a maximum amount of heat exchange between the top plate and a vessel located thereon, and ensures that only a minimum amount of heat will be conducted away from the top plate to'the surrounding supporting member.

A-further object of my invention is to provide a heating unit including a hermetically-sealed casing having a reflector'supported therein and spaced-fromthewalls'thereof.

A further obie'cto'f'my invention is to provide a heating unit including a' hermetically-sealed casing having areflector supported therein and electrically insulated from the walls thereof.

A further object of my invention is to provide a heating'unit-including a hermetically-sealed casing having a reflector supported therein in such a manner that when the reflector expands and contracts, it will not stress the walls of the which will have a small mass, and which may be 1! container.

A further object of my invention is to provide a heating unit including a hermetically-sealed container, one wall of said container providing a heating surface or hotplate, and .a reflector arranged in the container so as to limit the flow of convection'currents about the under side'of the heating surface or hotplate.

,A further object of my invention is to provide a range surface unit having a radiant heating element and a reflector located therein whereby the energy-radiated downwardly from the heating element, the top plate, and a cooking vessel placed upon the top plate will be reflected upwardly .and, therefore, conserve the dissipated energy from the heating element and increase the 'operating speed and efficiency of the unit.

' A further Object of my'invention is to provide a range surface unit, or the like, which will operate with aminimum amount of downward radiation, resulting in cooler operation of the connections.

Other objects of my invention will either be bodying my invention, or will be apparent from such description.

In the accompanying drawings:

Fig. i is a plan view of a device embodying my invention with the top plate removed;

Fig. 2 is a sectional view of the device, taken along line II-II of Fig. l;

Fig. 3 is a sectional view taken along line II-II of Fig. 1 showing a modification of the top plate;

Fig. 4 is a partial sectional view of the device sho n precedin figures; and

Fig. is a partial sectional view taken along line VV of Fig. 2.

Referring to the accompanying drawings, I show a heating unit ll comprising a sealed envelope i2 having a top portion l3 which may be used as the top plate or cooking surface of the unit, a, reflector l4 located within the envelope, and a heating element I5 insulatedly mounted intermediate the reflector and the top plate of such envelope.

The envelope [2 comprises the top plate or cooking surface l3, a main body portion [8, and a bottom terminal plate I! which may have eyelets 53 associated therewith for sealing leads or conductors thereto. The envelope [2 may be made of any suitable material which will be im-. pervious to gases, and which will be easy to form and work. However, it is preferred that such envelope be made of cold-rolled or chrome steel. It is preferred that the main body portion I8 of the envelope l2 be cylindrical in shape, substantially a shown, with the top plate I3 being welded to the main body portion in any suitable manner to form a gas-tight seal therewith. The bottom terminal plate l9 may likewise be welded to the cylindrical body portion to form a gastight seal therewith and may have an aperture 2i located therein, through which the exhaust tube 22 may be inserted and attached thereto for forming the final seal of the envelope when it is desirable to evacuate such envelope. Howver, it is to be understood that the top plate i3 and the bottom plate I!) may be attached to the body portion in any desired manner.

The top plate or cooking surface II of the heating unit comprise a central deformed portion 23 and a rim portion 24. The top plate I3 is made of any suitable material which will be able to withstand operations at high temperatures for long periods of time, either continuously or intermittently, without serious oxidation or disintegration, and which will be capable of withstanding a sharp blow or a sudden change in temperature, such as the spilling of ice water thereon, w hout injury while at a high temperature.

The bottom or inner surface of the central portion 23 of the top plate I3 should be permanently conditioned, such as roughened, blackened, or both, so that the top plate will be capable of absorbing a maximum amount of heat energy.

The central portion 23 of the top plate l3 may be fiat, although it is preferred that it be arched either concavely or convexly to prevent such top plate from warping and cracking with repeated operations.

The rim portion 24 of the top plate l3 may be of any shape desired. However, it is preferred that such rim be integral with the central portion, and that it have a vertical depending shoulder 25 with an exterior horizontal lip 26 associated therewith.

The reflector It comprises any suitable heatresisting material having a high reflecting power for radiant energy, such as nickel or aluminum, and has a highly polished surface located upon the top and bottom thereof. The reflector l4 should be formed into a very shallow dish-shaped structure having smooth contours. The reflector may be formed by a spherical spinning in which the radius of curvature is substantially greater than the diameter of the top plate, although such reflector need not be a paraboloid. The focus of the reflector, if it should have one, would then be located at a point above the surface of the top plate l3. However, it is to be understood that the important features of such reflector M are its shallowness, smoothness of curvature, and its high degree of reflectibillty. It is to be understood that, by having the reflector shallow and shaped like a dish with a smooth contour and a highly polished surface, substantially all the radiant energy striking such surface will be reflected toward the top plate, and that by having the dish as shallow as possible, the energy radiated downwardly will be reflected upwardly in a direct path rather than being reflected from one portion of the reflector to another before being reflected upwardly. Due to this reduction in the number of reflections, the efficiency of the reflector will be greatly increased, since the efliciency decreases with each additional reflection.

The periphery of the reflector I4 is spaced from the heating surface or top plate l3 for reasons more fully explained hereinafter, but the periphery is placed as close as practical to the heating surface or hotplate so as to obstruct and hinder the heated gas that would tend to pour over the periphery of the reflector during the heating-up period. If this heated gas is not obstructed in some manner it will pour over the periphery of the reflector during the heating-up period and will set up convection currents which will circulate between the reflector and heating surface or hotplate. These convection currents would take an appreciable amount of heat away from the heating surface or hotplate. Preferably, no portion of the reflector is further from the hotplate or heating surface than one-fourth the diameter of the hotplate or heating surface.

One reason for spacing the reflector N from the walls of the envelope I2 is to prevent cracking of insulators 34 and 48, the glass-to-metal seals 20, and opening up of the welded joints in the envelope by the expansion and contraction of the reflector. During the heating-up period the reflector expands very rapidly, and if, during this period, the periphery of the reflector contacts the side walls of the envelope l2, this expansion of the reflector will stress the bushings 34 and 48. the seals 29, and the welded joints in the container. These stresses would tend to crack the bushings and the seals, and open up the welded joints in the container, thereby exposing the inside of the container to the atmosphere which would cause the tungsten filament heating elements to oxidize and burn out, and would also cause the reflector to tarnish and thereby lose its reflecting qualities.

The heating unit l5 may comprise one or more heating elements; however, it is preferred that such unit be comprised of a primary and a secondary filament 3|] and 3|, respectively, which should be supported substantially parallel to the top plate I3. The filaments 30 and 3| are comprised of tungsten wire or any other similar material which can be operatedat a. high incandescent temperature, substantially -2500 C which willnot sag or evaporate appreciably when so heated, and which has a low-cold-resistance, permittingsuch filaments to come up to operating temperature. almost instantly-upon the application of power thereto. .In forming thefilamerits, the tungsten wire-or other suitable =material, due to. its ability-to operateflat a high incandescent temperature, may comprise smalldiameter wire whichmay be helically wound and the helix formed intoa circle having an overall length substantially shorter than the'elements of the heating units .now known to the-art. The heating element may then be supported substantially horizontally and within a relatively short distance from the bottom of the top. plate, permitting a maximum amountof direct radiation to the top plate.

The filaments 33 and3l, being comprised of tungsten or any other similar material which resists sag at high temperatures, need be supported .at only. a few pointsby aplurality of fingers 32 and 33, respectively, which may be rigidly mounted within any suitable insulator 34. By having the number of supporting fingersreduced to a minimum, it-wil1 be apparent that the energy conducted away from the filaments through suchfingers will likewise be aminimum, ensuring the high percentageof radiant energy desired in the device embodying my presentinvention. Although Ihave shown and described the fingers 32 and 33 for supporting the filaments 30 and 3 I, it will be understood that the filaments may be supported. in .the envelope 12 by any satisfactory means, I

The primary filamentllll as hereinabove described, is formed inanalmost-complete circle, and preferably has a diameter substantially twe thirds that of the top plate l3, whilethe secondary filament 3|=is of similar shape, being coaxially mounted slightly below the plane of the primary filament. and having adiameter preferably substantially one-half that of the top plate l3. However, it is to be understood that the .size and shape of the filaments may be varied depending upon the desired power rating of-the heating unit, andthat suchunit may have any number of filaments connectedto a power supply in any suitable manner.

The heating unit I I, as embodied in my present invention,.may be assembled by having the reflector l4 attached to the bottom plate ill. by means of one or more suitable support members 38 which may be inserted through and rigidly attachedto the reflector IA. The supports'38 are very slender so that when the reflector. l4 expands, they will. easily bend, and consequently will set up a minimumamount of stress in the walls of the envelope I2. .The reflector is electrically insulated from the supports. 38 and the envelope I2 by insulators 54 of lava or other suitable insulating material. The insulators 54 include a bushing member 52 and a ring-like member 53. It is important that the reflector 14 be electrically insulated from the envelope I2,so that in case one, of the heating filaments should break and fall down on the reflector a short circuit will not be set up through the envelope 12.

A main insulator 34, which may be of lava or other suitable materialma be located substantially in the center of the reflector M and maybe attached thereto by havingla. tongueiportion 39 thereofinserted through an aperture 40 located within the reflector l4, and by having a shoulder reflector and attached thereto.

portion resting uponthe top surface of the reflector. The insulator 34 may then be held rigidly within the aperture 40 by means of a plurality of suitable support members 42 rigidly attached to the top portion 43 of the insulator and to the reflector l4. However, it is understood that the insulator may be mounted by any other desirable method.

Rigidly attached to the top, of the main insulator. 34 ar a pluralit of fingers 32, which may be attached thereto in any suitable manner. These fingers32 are bent substantially horizontally or normally to the axis of rotation of the reflector, and having the free ends thereof wound into a small loop within which the primary filament may be loosely mounted. The fingers 32 comprise small-diameter wires, preferably of molybdenum, or. any other suitable refractory material, so that such fingers may have the small loop readily formed about the filament 30, ensuring minimum heat drain therefrom with no danger of melting or fusing thereto, and so that the free ends of such fingers will be capable of flexing relativel to the insulator to cushion any mechanical jar or vibration which wouldother- Wise injure the filament.

The secondary filament 3| is flexibly supported in a similar manner by a plurality of small fingers 33 which are preferably rigidly attached to the bottom surface of the top portion 43 of the main insulator 34. It is, therefore, obvious that the filaments 3U andv 3| Willbe flexibly mounted, in such a manner that they may expand and contract without distortion, and that such filaments will be protectedagainst mechanical vibrations or shock which would otherwise injure them.

The filaments 30 and 3| may be connected to a power supply through any suitable in-lead construction comprising a plurality of terminals 45, lead wires 4E, in-leads. 41, and .glass-to-metal sealsv 20. The terminal 45.111331 be insulatedly mountedupon the top surface of the reflector by grommets 4B of lava or other suitable material inserted through-smallv apertures 49 within the The lead wires 48 may then be rigidly attached to the terminals 45 and the insulating grommets 48 in such a manner that such lead wires 46 will be properly supported Without the aid of additional supports.

The in-leads 41. may be of molybdenum or other suitable material and after being inserted through. and attached tothe eyelets 53 by means of the .glass-to-metal seals 20 may be clamped orwelded tothe lead wires '46 ensuring. an insul'atedfgas-tight connection between the filaments 30 and 3! and any suitable power supply (not shown). .A ceramic-to-metal seal may be used instead of the glass-.to-metal seal 20 if so desired.

The eyelets '53 ma be of such material and shape that they may be welded or otherwise attached, to thebottom terminal plate I9 to form a gastight connection therewith, and also form a gas-tight metal-to-glass seal insulatedly between said eyelets and in-leads 41.

In view of the intense heat developed by the filamentspit is preferred that the terminals 45 and the lead wires 46 attached thereto be composed ofnickel, molybdenum or some other suitable material. If it be preferred, the bottom portion ofthe terminals 45 may be extended downwardly and towards the center to form the lead wires where they maybe operativelyassociated with the in-lead 41.

.If it be. desired, a plurality of plugs 44 operativelyassociated. with the in-leads 41 -maybe insulatedlymounted upon the bottom plate IQ for enabling the heating unit I I to be removably mount-ed upon and attached to any range having a receptacle to cooperate therewith. The plugs 44 may be insulatedly mounted upon any suitable cups 49 by means of insulating grommets 50. Ihe cups 49 may be rigidly attached tothe bottom plate i8 about the eyelets 53 in any suitable manner. The plugs 48 may be connected to the in-leads ll by means of a flexible wire 5! which will insulate the in-lead from an mechanical jar or vibration which might otherwise be tran mitted from the plug 48 to the in-lead 47, resulting in a rupture between said in-lead and its glass-to-metal seal 20.

It is, therefore, obvious that the reflector, and the filaments insulatedly mounted thereon as a unit, may be used with any top plate or may be located within any suitable envelope, that due to the iii-lead cons ruction having a vacuum seal with the bottom plate, such envelope may be evacuated or may have a predetermined inert atmosphere located therein, and that due to the plugs being located upon the bottom plate and operatively associated with the filaments, such heating unit may be readily interchangeably mounted upon any range having a suitable receptacle associated therewith.

By ha ing the heating element l5 and associated reflector i4 located within an envelope H which be sealed and evacuated, or filled with an in rt gas, the life of the filaments 30 and 3! may be greatly increased over those filaments which operate in an oxidizing atmosphere.

The top plate l3 may have the central portion 23 thereof deformed, as hereinabove described. By having the central portion deformed in the form of an arch, the plate may be unevenly heated without injury since the central portion of the deformation will be increasingly deformed, or in other words, the arch will become deeper and as the top plate cools, the deformation will return to its original position.

In operating the heating unit as hereinabove described, the filaments are connected to a power supply by any suitable switching means. Due to the low-cold-resistance of the filaments, the temperature of the filaments will instantly increase from the ambient to substantially 2500 C., and will cause substantially all of the electric power supplied thereto to be radiated therefrom in the form of heat energy. Approximately fifty per cent of the energy radiated from the heating elements will be radiated upwardl and the major portion of such energy will be absorbed by the heat-absorbing bottom surface of the top plate. However, that portion of the energy radiated upwardly that has not been absorbed by the top plate will be reflected downwardly. Such energy downwardly reflected from the top plate will contact the reflector, which, due to the highly polished top surface and the shallowness thereof, will efficiently reflect this energy back to the top plate in a direct path where the greater portion will be absorbed. However, a small portion of the re-reflected energy will again not be absorbed by the top plate but will be re-reflccted by such top plate and reflector as hereinabove described until all of such energy, except the small amount absorbed by the reflector, is absorbed by the top plate. This ability to re-reflect the unabsorbed energ is especiall important when the central portion of the top plate has an appreciable refiection factor, for it insures that a maximum amount of the energy dissipated by the filaments will eventually be absorbed by the top plate, and further serves to insulate the space below the heating unit from such dissipated heat energy. Further, the highly polished under surface of the reflector tends to prevent the heat absorbed by the reflector from being radiated downward into the body of the envelope l 2, thus further increasing the efficiency of the unit.

The balance of the radiant energy dissipated by the filaments not directly radiated upwardly will be radiated substantially downwardly in such a manner that it will contact the highly polished surface of the reflector, where, due to such reflector surface, the energy will be reflected directly upwardly upon the top plate. The greater portion of the reflected energy will be absorbed by the plate, however, a portion will be re-reflected downwardly to be again directly reflected back up against the top plate, as hereinabove described. Accordingly, it is obvious that that por tion of the radiant energy not absorbed by the bottom surface of the top plate will be directly re-reflected back and forth between the reflector and the top plate until the top plate absorbs substantially all the energy omitted by the heated filament.

When a vessel is placed upon a heating unit as lereinabove described, the energy absorbed by the top plate will be radiated, conducted and convected from the top plate to the bottom of the vessel. Should the bottom of the vessel be blackened or dirty, a. greater portion of this energy will be immediately absorbed While the remainder will be reflected downwardly towards the heating unit and will be re-refiected up to the bottom of the vessel by the reflector, and this cycle will continue until substantially all the energy dissipated by the heating element is absorbed by the bottom of the vessel.

It is, therefore, obvious that the top plate will radiate energy both upwardly and downwardly, while functioning as a transfer agent, as well as serving as a mechanical protective medium for the heating element and reflector surface located within the surface unit.

It is to be understood that for high speed and efficiency of the unit as a whole, the distance between the top of the reflector and the bottom of the top plate should be reduced to a minimum, and the edge or rim of the reflector should be as close to the bottom of the top plate as practicable to prevent radiant energy from coming into direct contact with the vertical sides 25 of the top plate and to muffle the escape of heated 4" gas into the body of the envelope l2, thus diverting some of the energy which otherwise would be directed to the bottom of the top plate.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

What I claim is:

1. A heating unit comprising a hermeticallysealed metal container having a wall providing a hotplate or heating surface, hermeticallysealed terminals projecting through a wall of the container, a plurality of heating elements exposed in said container and disposed closely adjacent the heating surface in planes substantially parallel thereto but in spaced relation thereto and dissipating heat thereto primarily by radiation, a metal reflector disposed within the container closely adjacent the heating elements on the side thereof remote from the heating surface, said reflector being substantially coextensive with the heating surface and spaced from the walls of the container, a metal support for supporting said reflector from a wall of the container, means electrically insulating said reflector from aid support, said reflector and said supporting means being constructed and arranged so that the reflector when it expands will not stress the walls of the container, means for supporting the heating elements in the container, and conductors disposed within the container and connecting the heating elements with the terminals.

2. A heating unit comprising a hermeticallysealed container having a wall providing a hotplate or heating surface, hermetically-sealed terminals projecting through a wall of the container, a plurality of heating elements exposed in said container and disposed adjacent the heating surface but in spaced relation thereto and dissipating heat thereto primarily by radiation, a reflector disposed within the container adjacent the heating elements on the side thereof remote from the heating surface, said reflector being substantially coextensive with the heating surface and having its periphery spaced from the walls of the container, a plurality of slender resilient rods supporting said reflector from a wall of the container, said resilient rods permitting said reflector to expand and contract without stressing the walls of the container, means for supporting the heating elements in the container, and conductors disposed within the container and connecting the heating elements to the terminals.

3. A heating unit comprising a hermeticallysealed container having a wall providing a hotplate or heating surface, hermetically-sealed terminals projecting through a wall of the container, a plurality of heating elements exposed in said container and disposed adjacent the heating surface in planes substantially parallel thereto but in spaced relation thereto and dissipating heat thereto primarily by radiation, a metallic reflector disposed within the container closely adjacent the heating elements on the side thereof remote from the heating surface, said reflector being substantially coextensive with the heating surface and having its periphery spaced from the walls of the container, means for supporting the reflector from a wall of the container, said reflector and said supporting means being constructed and arranged so that the reflector when it expands will not stress the walls of the container, means for supporting the heating elements in the container, and conductors disposed within the container and connecting the heating elements with the terminals.

4. A heating unit as claimed in claim 3 wherein the peripheral portion of the reflector is inclined toward the peripheral portion of the heating surface.

5. A heating unit comprising a top plate, a plurality of helically wound heating elements ringlike in form disposed in planes each substantially parallel to said plate, the periphery of one heating element enclosing a larger area than that of the other, a shallow reflector disposed close to said elements, a central supporting structure stationarily mounted with respect to said reflector, and means comprising a plurality of widely spaced fingers mounted upon said supporting structure for supporting the respective heating elements, both elements being disposed to radiate heat directly to said top plate and to said reflector.

6. A heating unit comprising a top plate, a plurality of helically wound heating elements ringlike in form disposed in planes each substantially parallel to said plate, the periphery of one heating element enclosing a larger area than that of the other, a shallow reflector disposed close to said elements, a central supporting structure mounted on said reflector, and means comprising a plurality of widely spaced fingers mounted upon said supporting structure for supporting the respective heating elements, both elements being disposed to radiate heat directly to said top plate and to said reflector.

'7. A heating unit comprising a top plate, a plurality of helically wound small-diameter heating elements ringlike in form disposed in planes each substantially parallel to said plate, the periphery of the heating element closer to said plate enclosing a larger area than that of the other, a shallow reflector disposed close to said other heating element, a central supporting structure mounted on said reflector, and means comprising a plurality of widely spaced fingers mounted upon said supporting structure for supporting the respective heating elements, both elements being disposed to radiate heat directly to said top plate and to said reflector.

8. A heating unit comprising a hermetically sealed container provided with a top plate providing a heating surface, a plurality of helically wound heating elements disposed in said container in planes each substantially parallel to said plate, and adjacent thereto, the perimeter of one heating element in one plane falling entirely within the projected area of the other, a shallow reflector disposed close to and under said elements within said sealed container, a centrally disposed supporting structure, and a plurality of widely spaced fingerlike supports carried by said supporting structure within said sealed container for supporting the respective heating elements in position to radiate heat directly to said top plate and to said reflector.

9. A heating unit as claimed in claim 8 wherein the reflector is spaced from the walls of the container.

10. A heating unit comprising a hermeticallysealed container having a wall providing a hotplate or heating surface, hermetically-sealed terminals projecting through a wall of the container, a heating element or elements exposed in said container and disposed adjacent the heating surface and substantially parallel thereto but in spaced relation thereto and dissipating heat thereto primarily by radiation, a metallic reflector disposed within the container closely adjacent the heating elements on the side thereof remote from the heating surface, said reflector being substantially coextensive with the heating surface and having its periphery spaced from the Walls of the container, means for supporting the reflector from a wall of the container, said reflector and said supporting means being constructed and arranged so that the reflector when it expands will not stress the walls of the container, means for supporting the heating elements in the container, and conductors disposed within the container and connecting the heating elements with the terminals.

EUGENE W. BEGGS.

' CERTIFICATE OF CORRECTION. I Patent No. 2,529,L 51. September 1h, 191g.

EUGENE w. BEGGS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page ii, sec- 0nd column, line 25, for "omitted" read -emitted--; and that the said Letters Patent should be read with this Correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25rd day of November, A. D. 19%.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

